Query performance - Difference between OPERATOR - Exists and IN

Question

Hi,
I Have Two Tables VD,ID .Each table containg one lakh rows.
CREATE TABLE VD (
SRNO NUMBER(12) ,
UNIT Varchar2(2) ,
CREATE TABLE ID ( SRNO NUMBER(12),
PID Varchar2(2) ,
Sid Varchar2(20)
In my Application i need to display Column(SRNO) from table VD If the Column(SRNO)exists in Table ID
for the given PID and SID.
Which query has better performance in below Queries ?
Select SRNO from VD Where SRNO in( Select SRNO From ID Where PID = :A
And Sid = :B )
Select SRNO from VD V Where Exists( Select 'X' From ID Z Where Z.PID = :A
And Z.Sid = :B
And Z.SRNO = V.SRNO )
Version : Oracle 10g
Thanks ....
Sathi

Answer 1

user10732947 wrote:
pls refer to :-)
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:953229842074
And which part are you referring to specifically?
It backs up what Toon already mentioned....
ops$tkyte@ORA10GR2> SELECT /* EXISTS example */
  2           e.employee_id, e.first_name, e.last_name, e.salary
  3    FROM employees e
  4   WHERE EXISTS (SELECT 1 FROM orders o                  /* Note 1 */
  5                    WHERE e.employee_id = o.sales_rep_id   /* Note 2 */
  6                      AND o.customer_id = 144);
Execution Plan
Plan hash value: 551415261
| Id  | Operation                    | Name      | Rows  | Bytes | Cost (%CPU)|
|   0 | SELECT STATEMENT             |           |    67 |  4087 |    49   (3)|
|   1 |  NESTED LOOPS                |           |    67 |  4087 |    49   (3)|
|   2 |   SORT UNIQUE                |           |    67 |  1139 |    14   (0)|
|*  3 |    TABLE ACCESS FULL         | ORDERS    |    67 |  1139 |    14   (0)|
|   4 |   TABLE ACCESS BY INDEX ROWID| EMPLOYEES |     1 |    44 |     1   (0)|
|*  5 |    INDEX UNIQUE SCAN         | EMP_PK    |     1 |       |     0   (0)|
Predicate Information (identified by operation id):
   3 - filter("O"."CUSTOMER_ID"=144)
   5 - access("E"."EMPLOYEE_ID"="O"."SALES_REP_ID")
ops$tkyte@ORA10GR2>
ops$tkyte@ORA10GR2> SELECT /* IN example */
  2           e.employee_id, e.first_name, e.last_name, e.salary
  3      FROM employees e
  4     WHERE e.employee_id IN (SELECT o.sales_rep_id         /* Note 4 */
  5                               FROM orders o
  6                              WHERE o.customer_id = 144);
Execution Plan
Plan hash value: 551415261
| Id  | Operation                    | Name      | Rows  | Bytes | Cost (%CPU)|
|   0 | SELECT STATEMENT             |           |    67 |  4087 |    49   (3)|
|   1 |  NESTED LOOPS                |           |    67 |  4087 |    49   (3)|
|   2 |   SORT UNIQUE                |           |    67 |  1139 |    14   (0)|
|*  3 |    TABLE ACCESS FULL         | ORDERS    |    67 |  1139 |    14   (0)|
|   4 |   TABLE ACCESS BY INDEX ROWID| EMPLOYEES |     1 |    44 |     1   (0)|
|*  5 |    INDEX UNIQUE SCAN         | EMP_PK    |     1 |       |     0   (0)|
Predicate Information (identified by operation id):
   3 - filter("O"."CUSTOMER_ID"=144)
   5 - access("E"."EMPLOYEE_ID"="O"."SALES_REP_ID")Two identical Execution plans...